When I first learned about the limit it greatly disturbed my algebraic thinking, but I pushed the thought aside for a while, and now it's come back.
Take for example:
We have the expression
, which is equivalent to
On the left, substituting in x we get an undefined answer, substituting into the right expression however, we get 2.
Aren't the two expression as perfect as each other? Then why do they give a different result when you substitute in x?
It's like we are, by manipulating the number, forcing it to give a certain answers against its will.